1. Scope of the Invention
The present invention relates to digital radio modulation and more particularly, modulation of a data word in parallel.
2. Description of Related Art
Data or digitized analog information, is typically transmitted via radiowaves from a transmitter to a receiver. There are many ways of modulating the data to encode the digital information. One such way is to map data bits to phase shifts of a carrier wave. Therefore, a carrier wave has phase shifts which are modulated according to the input data transmitted and received at a receiver which then identifies the phase shift and the carrier signal to recover the encoded data.
Two such types of modulation are quadrature phase shift keyed (QPSK) modulation, and differential quadrature phase shift keyed (DQPSK) modulation.
There are also frequency modulation schemes in which data is encoded as the frequency of the carrier such as frequency shift keying (FSK) and continuous FSK (CPFSK).
There are also amplitude modulation schemes such as two or four level amplitude modulation (AM), and quadrature amplitude modulation (QAM).
In each of the above modulation schemes, a change in the frequency, phase, or amplitude modulates a single-bit, or several bits, of information being transmitted sequentially.